This is an extensive cooperative study including the Perinatal Research Study as one of the collaborating groups. Serial clinical data, blood specimens, as well as throat swabs, placental tissue speciments, and samples from newborns are being obtained to determine insofar as possible the role of infections and the productions of abnormal pregnancy outcomes. First, the clinically reported infections in these studies are being documented by serological techniques ad correlated with pregnancy outcomes. Second, 4,000 abnormal pregnancies and 4,000 controls are being studied utilizing 11 viral and protozoal antigens. The antibody responses are being correlated with pregnancy outcomes to determine possible role of these agents in the production of abnormal pregnancies. Third, the cord sera from 30,000 children are tested for IgM antibody levels as a means of identifying high-risk children and specific IgM tests for five key antigens are being used to identify specific antibody in the baby. Additional studies include investigations of HLA antibody in pregnant women.